The present technology relates to a solid-state imaging apparatus and an electronic apparatus such as a camera including the solid-state imaging apparatus.
Electronic apparatuses such as a digital video camera and a digital still camera include the solid-state imaging apparatus. Such electronic apparatuses include a complementary metal oxide semiconductor (CMOS) type image sensor chip or a charge coupled device (CCD) type image sensor chip, for example, as the solid-state imaging apparatus.
In the solid-state imaging apparatus, a plurality of pixels are arranged in an array on an imaging surface of a substrate. Each of the plurality of pixels is provided with a photoelectric conversion unit. The photoelectric conversion unit is, for example, a photodiode, and receives light, which is incident as a subject image through an external optical system including an imaging lens, on a light receiving surface and photoelectrically converts the light, thereby generating a signal charge.
In the substrate constituting the solid-state imaging apparatus, a cover glass is disposed above a surface on which the incident light is incident as the subject image. The solid-state imaging apparatus has, for example, a “cavity structure”, and an air layer is interposed between the cover glass and the substrate on which the pixels are arranged. Otherwise, the solid-state imaging apparatus has, for example, a “cavity-less structure”, and the air layer is not interposed between the cover glass and the substrate on which the pixels are arranged, and for example, a solid layer such as resin is interposed between the cover glass and the substrate on which the pixels are arranged. It is suitable that the “cavity-less structure” can prevent the occurrence of problems such as “warping”, “peeling”, and “decrease in sensitivity due to interface reflection” caused by a gap of the “cavity structure” (for example, see Japanese Patent Application Laid-Open No. 2007-311454 (for example, FIGS. 1 and 5)).
Moreover, a band-pass filter such as an infrared cut filter may be provided on one surface of the cover glass (for example, see Japanese Patent Application Laid-Open No. 2010-186818 (for example, FIG. 29)). For example, a plurality of deposited films are stacked and a reflection-type infrared cut filter is provided, thereby enhancing the image quality for a captured image of a subject image of visible light (for example, see Japanese Patent Application Laid-Open No. 2001-203913 (for example, paragraph [0014])).
In the solid-state imaging apparatus, a ghost (flare) occurs on the captured image due to reflected diffraction light caused by the pixels periodically arranged on the imaging surface of the substrate, so that the image quality may be deteriorated. Specifically, when incident light is incident from above as the subject image to periodic structures such as microlenses periodically disposed corresponding to the plurality of pixels, the incident light is diffracted by the periodic structures and some of the incident light is reflected above as the reflected diffraction light. For example, light reflected on the surface of the microlens or the substrate becomes the reflected diffraction light. Then, the reflected diffraction light is incident on and reflected by elements such as the cover glass, the infrared cut filter, and an external lens disposed above the substrate. Subsequently, when the reflected diffraction light reflected by the elements is re-incident on the pixels, the ghost occurs on the captured image. In order to solve these problems, various techniques have been proposed (for example, see Non-Patent Document, Shohei Matsuoka et al., “Reflection diffraction ghost caused by imaging element”, Thirty-fourth Optical Symposium proceedings, The Optical Society of Japan, An Affiliate of Japan Society of Applied Physics, Jul. 2, 2009, p. 11 to p. 12; Non-Patent Document, Yasuhiro Aono et al., “Evaluation method of digital camera optical system”, Twenty-seventh Optical Symposium proceedings, The Optical Society of Japan, An Affiliate of Japan Society of Applied Physics, Jun. 20, 2009, p. 1 to p. 4; and Japanese Patent Application Laid-Open No. 2011-082266 (for example, paragraphs [0002], [0026])).